Using buttons of a website for automation

My shutters are controlled through a local website (with unknown endpoints and unknown API). The network traffic is complicated and not obvious understandable. Manually I start the shutter by pressing the button.

The site is quite easy, I can press the button and start the shutter from the console with

// Den Wert des Select-Elements auf "wa_E3" setzen
document.getElementById("KanalSelectBox").getElementsByTagName("select")[0].value = "wa_E6";
// Ein "change" Event auslösen, um das Dropdown-Menü zu aktualisieren
document.getElementById("KanalSelectBox").getElementsByTagName("select")[0].dispatchEvent(new Event('change'));

This would solve my automation issue controlling the shutters.
How can I realize the integration in HA?
(browser_mod seems to create sites, but no action to existing sites)
(multiscraper sends select commands, but a click?)
Any ideas welcome! Thanks

I moved finally to browserless website.
[GUIDE] Scraping dynamic websites with browserless + multiscrape. v2 update - Community Guides - Home Assistant Community (
still not working but im quite close to solve it